✨ implemented an indentation character #520

An optional parameter for dump() allows to set the character to use for
indentation (default: space). In case a JSON value is serialized to an
output stream, its fill character is used (and can be set with
std::setfill).

doc/examples/operator_serialize.cpp

@@ -16,4 +16,5 @@ int main()
     // serialize with indentation
     std::cout << std::setw(4) << j_object << "\n\n";
     std::cout << std::setw(2) << j_array << "\n\n";
+    std::cout << std::setw(1) << std::setfill('\t') << j_object << "\n\n";
 }